The instruction is defined as:

• ADDRESSES
  • 1- Input Address
    • (it defines where to read from: Memory or Input device)
  • 2- Output Address
    • (it defines where to write: Memory or Output device)
• INSTRUCTIONS
  • 3- Instruction for case 0
    • (executed when the bit in Path Selector address is 0)
  • 4- Instruction for case 1
    • (executed when the bit in Path Selector address is 1)

Execution of one instruction: bit copy and path selection phases.

• BIT COPY
  • 1- input phase (Read from input address)
  • 2- output phase (write to output address a copy of the bit from input address)
• PATH SELECTION
  • 3- instruction selection phase (instruction selection from Path Selector address, address that could be written or not in the output phase).

https://en.wikipedia.org/wiki/Microcode https://en.wikipedia.org/wiki/One_instruction_set_computer